Production of backing component for carpet products

ABSTRACT

Disclosed are plastic compositions for a carpet backing having from about 5 to about 25% by weight PVC resin, from about 5 to about 25% by weight plasticizer, and from about 50 to about 90% by weight filler. In a preferred embodiment, the plastic composition is about 15% by weight Geon-138, about 15% by weight di-isononyl phthalate, and about 70% by weight fly ash. Also disclosed are methods for forming backings for floorcoverings using the disclosed plastic compositions. In preferred embodiments, a plastic composition is applied through a slot-die directly to the underside of a carpet or alternatively onto a conveyor belt on top of which the carpet or floorcovering may be subsequently positioned.

CROSS REFERENCE TO RELATED APPLICATION

This application claims benefit of U.S. Provisional Patent ApplicationSer. No. 60/690,256, filed Jun. 14, 2005, the contents of which areincorporated herein by reference.

FIELD OF THE INVENTION

This invention relates to compositions, apparatuses, and methods forforming a backing component for carpet products, including carpet tiles.

BACKGROUND OF THE INVENTION

Carpet products, including carpet tiles, typically have afiber-containing pile face attached to a primary backing and, attachedto the underside of the primary backing, a multi-component secondarybacking containing a variety of materials that impart desired physicalproperties, including weight, stability, stiffness, durability,under-foot comfort, and resistance to cupping and curling, among otherproperties.

One of the materials conventionally used in carpet tile secondarybacking is polyvinyl chloride (“PVC”). See, for example, U.S. Pat. Nos.,4,010,301, 4,010,302, and 5,560,972 that are incorporated herein byreference. As U.S. Pat. No. 5,560,972 explains, such a secondary backingis typically applied as a liquid having a viscosity of approximately10,000-20,000 centipoise. Column 7, lines 24-39. The liquid is appliedto the carpet web or onto a conveyor belt by depositing it in a puddlethat is then metered to a desired thickness with a doctor bar orcalendar roll.

It is often desirable to incorporate inexpensive fillers (such as flyash, dirt, etc.) into the backing composition and thereby reduce theunit cost of the composition. Incorporation of these fillers increasesthe viscosity of the backing composition. However, a doctor bar is notsuitable for such high viscosity compositions because it is verydifficult precisely to meter such compositions to the desired thickness,and use of a calendar roll with such high viscosity compositions canresult in excessive conveyor belt wear and other problems. Thus, simplypouring onto a carpet web or a conveyor belt the composition havingfiller (and thus a high viscosity) and doctoring or calendar rolling thematerial to a precise gauge is extremely difficult. This inventionprovides an alternative apparatus and method for forming carpet backingsfrom compositions having a high filler content whereby the compositionis dispensed in a sheet-like form through a slot die.

Extruders have been used to extrude PVC into a sheet-like form. Whilemany types of extruders exist, they all operate in substantially thesame way. Solid phase materials (such as plastic powder or solidpellets) are supplied into a cavity in the extruder. Energy is impartedto the solid materials in the cavity to convert them into a phase(semi-solid or liquid) capable of flowing through the extruder die. Theenergy to effectuate phase change may be imparted by supplying heat tothe extruder, increasing the pressure in the extruder, and/or may resultsimply by shearing of the materials in the extruder cavity.

Extruders, however, are not ideal for extruding materials having a highfiller content. Extruders represent a large capital investment and areextremely costly to maintain and repair. The fillers in compositionshaving high filler content do not melt or otherwise change phase duringthe extrusion process. These grit-like fillers thus wear excessively onthe extruder parts and thus require their frequent replacement, which isextremely costly. Thus, use of extruders with compositions having highfiller content is undesirable.

SUMMARY OF THE INVENTION

This invention addresses the problems of previous backing compositionsand methods for forming backing compositions by providing plasticcompositions for a carpet backing having from about 5 to about 25% byweight PVC resin, from about 5 to about 25% by weight plasticizer, andfrom about 50 to about 90% by weight filler. The PVC composition ispreferably Geon-138, Geon-121, Formolon-40, VC-216 or combinationsthereof, and is more preferably about 15% by weight Geon-138. Theplasticizer is preferably di-isononyl phthalate, di-isoheptyl phthalate,di-isoundecyl phthalate or combinations thereof, and is more preferablyabout 15% by weight di-isononyl phthalate. The filler is preferably flyash, dirt, calcium carbonate or combinations thereof, and is morepreferably about 70% by weight fly ash. The plastic compositionpreferably has a viscosity of from about 30,000 to about 50,000centipoise. The plastic composition may be applied as a floorcoveringbacking and preferably has a thickness of from about 20 to about 75mils, and more preferably has a thickness of about 25 mils.

Also disclosed are methods for forming a floorcovering by preparing aplastic composition according to the above and forming the plasticcomposition into a backing layer by preferably feeding the plasticcomposition through a slot-die. In a preferred embodiment, the plasticcomposition is prepared in a holding tank and pumped from the holdingtank to the slot die with a gear pump or an extruder. In otherembodiments, the backing layer exiting the slot-die is positioneddirectly onto a conveyor belt and a face of the floorcovering ispositioned above the backing layer. Additional layers, such as astabilizing layer, may be positioned between the backing layer and theface. The backing layer exiting the slot-die may also be positioned onthe underside of a face of the floorcovering. The disclosed compositionsmay be used in the backing of a variety of floorcovering productsincluding, but not limited to, vinyl floorcovering and tiles, broadloomcarpet, six foot carpet, and carpet tiles.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic drawing of a preferred embodiment of the apparatusof the present invention.

FIG. 2 is a schematic drawing according to another embodiment of theinvention.

FIG. 3 is a schematic drawing according to yet another embodiment of theinvention.

FIG. 4 is a schematic drawing according to a further embodiment of theinvention.

DETAILED DESCRIPTION OF THE INVENTION

This invention provides more effective and less expensive compositions,apparatuses and methods for forming a plastic layer component—describedherein as a plastisol—of a carpet backing, particularly a carpet tilesecondary backing. While the apparatuses and methods of this inventioncan be used for forming a wide variety of types and thicknesses ofplastisols, they are particularly effective for use with compositionshaving a high filler content. The plastisol according to the presentinvention is desirably 20 to 75 mils thick, more desirably 20 to 50 milsthick, and most desirably 25 mils thick (i.e. 0.025 inches). Theplastisol is formed from the following components:

Component Amount by weight PVC resin 5-25% Plasticizer 5-25% Filler50-90% 

The PVC resin is the plastic component to the plastisol. Suitable PVCresins include: Geon-138 and Geon-121, produced by PolyOne Corporation;Formolon-40, produced by Formosa Plastics Corp.; VC-216, produced byBorden Chemical Co.; and combinations thereof. A particularly preferablePVC resin is Geon-138 in an amount of approximately 15% by weight.

The plasticizer is added to improve the flow and viscositycharacteristics of the plastisol. Suitable plasticizers includedi-isononyl phthalate, di-isoheptyl phthalate, di-isoundecyl phthalateand combinations thereof. A particularly preferable plasticizer isdi-isononyl phthalate in an amount of approximately 15% by weight.

The filler can be any material which allows the amount of plasticizerand/or PVC resin in the plastisol to be reduced, and are usuallyinexpensive relative to the cost of the plasticizer and PVC resin.Suitable fillers include fly ash, dirt, calcium carbonate andcombinations thereof. A particularly preferable filler is fly ash in anamount of approximately 70% by weight.

When mixed, the plastisol can have a viscosity of approximately 30,000to 50,000 centipoise. Note that while the apparatus and methods of thisinvention are disclosed for use with a plastisol, they may be used witha variety of other materials, including polyvinylbutyral andhighly-filled asphalt-based products, such as those disclosed in U.S.Pat. Nos. 5,030,497 and 5,096,764, the entireties of which are hereinincorporated by reference.

The plastic sheet of this invention may be formed by dispensing theplastic material, such as the above-described plastisol, through a slotdie having a horizontal slot that may be, for instance, approximately 25mils in height and approximately 80 inches in width. The slot die ispositioned immediately above and/or adjacent a conveyor belt. In apreferred embodiment, the plastic sheet is deposited directly on theconveyor belt, after which optional additional backing components suchas a fiberglass scrim and a second coating of PVC resin or plastisol canbe, but does not have to be, applied atop the plastic sheet. A carpetweb is then positioned directly on top of the plastic sheet or on top ofthe backing composite to bond thereto. In an alternative embodiment, anupside down carpet web rests on the conveyer belt or other system sothat the web advances at the same speed as the exiting plastic sheet,permitting the sheet to lie on and be bonded to the advancing web.Unlike the prior doctoring method described above, the slot die iseasily able to form sheets of consistent gauge from compositions havinghigh filler content and thus high viscosities.

In one embodiment of this invention, after mixing, the plastisol of thisinvention may be placed in a holding tank, from which it is removed byone or more diaphragm pumps that transfer the plastisol from the holdingtank to a gear pump that forces the composition through a slot die fromwhich the desired sheet is dispensed. The gear pump imparts a constantpressure to the composition and ensures a smooth, continuous flow of thecomposition from the slot die. Thus, the sheet exiting the slot die isof consistent gauge. A gear pump and its parts are less expensive thanan extruder and thus cheaper to repair should they incur damage from thefiller in the composition.

EXAMPLE 1

In one embodiment of this invention the following materials were mixedutilizing a Nauta mixer (although other mixers, such as a horizontalplow mixer, may be used) to form a plastisol:

Component Amount by weight Geon-138 (PVC resin) 15% di-isononylphthalate (plasticizer) 15% Fly ash (filler) 70%

As is illustrated in the schematic diagram of FIG. 1, the plastisol 10was transferred to a plastisol holding tank 20 illustrated in FIG. 1.Two diaphragm pumps 22 and 24, such as those manufactured by Wilton andpreferably having three-inch inlet and outlet ports, were used totransfer the plastisol to a gear pump 26. Gear pump 26, such as the Maaggear pump (model number RX 110/110), had a flow rate of between 70pounds/minute and 90 pounds/minute and preferably approximately 83pounds/minute.

EXAMPLE 2

In one embodiment (see FIGS. 1 and 2), gear pump 26 feeds a slot die 28positioned so that a sheet 30 of plastisol 10 dispensed from the slotdie 28 rests on an advancing conveyor 34. Sheet 30 is desirably 20 to 75mils thick, more desirably 20 to 50 mils, and most desirablyapproximately 25 mils thick (0.025 inches). After deposit of the sheet30 on the conveyor 34 (in FIGS. 1 and 2), additional backing structuresmay be, but do not have to be, introduced on top of the sheet 30. Forexample, in a preferred embodiment, a stabilizing layer 16 (such as afiberglass scrim) is positioned on top of the sheet 30, after whichanother layer of PVC 18 (which may be introduced via another slot die orby a traditional metering process) is applied atop the fiberglass scrim16. A carpet web 32 is then positioned on top of the upper layer of PVC18, which serves to bond the carpet web 32 to the underlying backingcomposite. FIG. 2 illustrates the cross-section of this finished carpetcomposite 36, having a carpet web or facecloth 32 that includes yarn 17tufted into a primary backing fabric 19 and secured in place with anadhesive layer 23. Individual carpet tiles may be cut from the resultingfinished carpet composite 36 utilizing techniques well known in theindustry.

EXAMPLE 3

In another embodiment (see FIGS. 3 and 4), gear pump 26 feeds slot die28 positioned so that the sheet 30 of plastisol 10 dispensed from theslot die 28 rests on an advancing upside down carpet web 32 that itselfrests on conveyor 34. Sheet 30 is desirably 20 to 75 mils thick, moredesirably 20 to 50 mils and most desirably approximately 25 mils thick(0.025 inches). Deposit of the sheet 30 on the advancing carpet web 32forms a carpet composite 40 from which individual tiles may be cututilizing techniques well known in the industry. As with the embodimentof FIG. 2, additional layers of material may be deposited on top of thesheet 30 to form alternative carpet composites than that illustrated inFIG. 4.

EXAMPLE 4

In another embodiment of this invention the following materials aremixed to form a plastisol:

Component Amount by weight Geon-121 (PVC resin) 10% Formolon-40 (PVCresin) 10% di-isoheptyl phthalate (plasticizer) 15% Fly ash (filler) 65%

EXAMPLE 5

In a further embodiment of this invention the following materials aremixed to form a plastisol:

Component Amount by weight VC-216 (PVC resin) 25% di-isononyl phthalate(plasticizer) 25% calcium carbonate (filler) 50%

EXAMPLE 6

In yet another embodiment of this invention the following materials aremixed to form a plastisol:

Component Amount by weight Geon-138 (PVC resin) 10% di-isoheptylphthalate (plasticizer) 10% di-isoundecyl phthalate (plasticizer) 5% flyash (filler) 75%

EXAMPLE 7

In yet a further embodiment of this invention the following materialsare mixed to form a plastisol:

Component Amount by weight Geon-138 (PVC resin) 5% di-isononyl phthalate(plasticizer) 5% Fly ash (filler) 90%

As will be appreciated by those skilled in the art, the composition ofplastisol 10 can be modified by the use of differing amounts of theabove-specified components, by substituting, adding or deletingcomponents, and by modifying the above-described processing steps. Suchmodifications may alter the physical and chemical properties of theplastisol. Notwithstanding such modifications, the sheet-forming methodsand apparatus described herein will usually be effective provided thatthe plastisol (or other plastic paste) is of relatively high viscosity(i.e., has a viscosity in the range of 10,000 to 75,000 centipoise). Torealize some of the goals of this invention, such as decreased wear andtear on equipment and reduced cost of the plastisol, a plastisol with aviscosity of between 30,000-50,000 centipoise is particularly desirable.Moreover, the compositions disclosed herein may be used in the backingof a variety of floorcovering products including, but not limited to,vinyl floorcovering and tiles, broadloom carpet, six foot carpet, andcarpet tiles.

The foregoing is provided for the purpose of illustrating, explainingand describing embodiments of the present invention. Furthermodifications and adaptations to these embodiments will be apparent tothose skilled in the art and may be made without departing from thespirit of the invention or the scope of the claims.

1-20. (canceled)
 21. A method for forming a floorcovering comprising: a.preparing a plastic composition by mixing from about 5 to about 25% byweight PVC resin, from about 5 to about 25% by weight plasticizer, andfrom about 50 to about 90% by weight filler; and b. forming the plasticcomposition into a backing layer by feeding the plastic compositionthrough a slot-die.
 22. The method of claim 21, wherein the plasticcomposition is prepared in a holding tank and pumped from the holdingtank to the slot die through a gear pump.
 23. The method of claim 21,wherein: a. the plasticizer is selected from the group consisting ofdi-isononyl phthalate, di-isoheptyl phthalate, di-isoundecyl phthalateand combinations thereof; and b. the filler is selected from the groupconsisting of fly ash, dirt, calcium carbonate and combinations thereof.24. The method of claim 23, wherein the plastic composition comprisesabout 15% by weight PVC resin, about 15% by weight di-isononylphthalate, and about 70% by weight fly ash.
 25. The method of claim 21,wherein the backing layer exiting the slot-die is positioned directlyonto a conveyor belt.
 26. The method of claim 25, further comprisingpositioning a face of the floorcovering above the backing layer.
 27. Themethod of claim 26, further comprising positioning a stabilizing layerbetween the backing layer and the face.
 28. The method of claim 27,wherein the floorcovering comprises carpet.
 29. The method of claim 21,wherein the backing layer exiting the slot-die is positioned on theunderside of a face of the floorcovering.
 30. The method of claim 29,wherein the floorcovering comprises carpet.